#!/usr/bin/python3

import sys
import os
import hashlib
import pickle
from subprocess import run

tasks = []

class Task:
    name = ""
    ifchange = []
    commands = []
    
    def show(self):
        print(self.name)
        print(self.ifchange)
        print(self.commands)


dragon_ascii = """
 ,,
`""*$b..
     ""*$o.
         "$$o.
           "*$$o.
              "$$$o.
                "$$$$bo...       ..o:
                  "$$$$$$$$booocS$$$    ..    ,.
               ".    "*$$$$SP     V$o..o$$. .$$$b
                "$$o. .$$$$$o. ...A$$$$$$$$$$$$$$b
          ""bo.   "*$$$$$$$$$$$$$$$$$$$$P*$$$$$$$$:
             "$$.    V$$$$$$$$$P"**""*"'   VP  * "l
               "$$$o.4$$$$$$$$X
                "*$$$$$$$$$$$$$AoA$o..oooooo..           .b
                       .X$$$$$$$$$$$P""     ""*oo,,     ,$P
                      $$P""V$$$$$$$:    .        ""*****"
                    .*"    A$$$$$$$$o.4;      .
                         .oP""   "$$$$$$b.  .$;
                                  A$$$$$$$$$$P
                                  "  "$$$$$P"
                                      $$P*"
    mls                              .$"
                                     "
"""


help_message = """
tasks :
A simple way to define tasks and execute them.

Usage: tasks file
"""
def print_help():
    """ print help and usage """
    print(dragon_ascii)
    print(help_message)

def check_if_file(in_file, check_file):
    """ Checks it the given file exists, else print error and exit """
    if os.path.isfile(check_file):
        return True
    else:
        print("In " + in_file + " : " +  check_file + " is not a file")
        exit(1)

def getsha1(filename):
    """ Return the sha1 value of the given filename """
    with open(filename, 'rb') as file_to_check:
        data = file_to_check.read()
        sha1_returned = hashlib.sha1(data).hexdigest()
    return sha1_returned

def do_tasks(tasks_file):
    """ Do the tasks stored in tasks list """
    stored_entries = {}
    if os.path.isfile("." + tasks_file + ".bin"):
        stored_entries = pickle.load(open("." + tasks_file + ".bin", 'rb'))

    for task in tasks:
        redo_task = False

        """ If change check """
        for f in task.ifchange:
            if stored_entries.get(f, "")  != getsha1(f):
                stored_entries[f] = getsha1(f)
                redo_task = True

        """ Update the stored_entries for this tasks file """
        pickle.dump(stored_entries, open("." + tasks_file + ".bin", 'wb'))

        if len(task.ifchange) < 1:
            redo_task = True

        if redo_task == False:
            continue
        
        """ Run Commands of the Task """
        for c in task.commands:
            print("+ " + c)
            p = run(c.split())
            if p.returncode != 0:
                print(p)
                print("Task Failed : " + task.name , file=sys.stderr )
                exit(p.returncode)

def get_tasks(filename):
    """ Take a tasks file and convert it to Task structures, stored in a global tasks list """
    number_of_tasks = 0
    # Possible sections : comment, ifchange, commands
    current_section = ""
    
    with open(filename, 'r') as f:
        for line in f.readlines():
            l = line.strip()

            if len(l) > 0 and l[0] == '*':
                number_of_tasks += 1
                tasks.append(Task())
                tasks[number_of_tasks - 1].name = l[1:].strip()
                tasks[number_of_tasks - 1].ifchange = []
                tasks[number_of_tasks - 1].commands = []
                current_section = "comment"
                continue
            elif l == "#ifchange":
                current_section = "ifchange"
                continue
            elif l == "#do":
                current_section = "commands"
                continue

            if current_section == "ifchange":
                for entry in l.split():
                    check_if_file(filename, entry)
                    tasks[number_of_tasks - 1].ifchange.append(entry)
            elif current_section == "commands" and len(l) > 0:
                tasks[number_of_tasks - 1].commands.append(l)

def main():
    tasks_file = "main.tsk"

    if len(sys.argv) > 1:
        if os.path.isfile(sys.argv[1]):
            tasks_file = sys.argv[1]
        else:
            print_help()
            exit(1)
    
    get_tasks(tasks_file)
    print("<-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <->")
    for task in tasks:
        print("For task named " + task.name)
        task.show()
    print("<-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <-> <->")
    do_tasks(tasks_file)

if __name__ == "__main__":
    main()
    pass